Term
| What are the two groups of hormones derived from tyrosine? |
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Definition
Thyroid hormones, ex - thyroxine Catecholamines, ex - EPI |
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Term
| Explain the adrenal glansds |
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Definition
*located above the kidneys *secrete EPI and NE in response to Ach stimulation |
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Term
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Definition
*both neurohormones and neurotransmitters *NE and EPI are produced by the adrenal medulla and are both water soluble *secreted like peptide hormones |
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Term
| Explain the synthesis of catecholamines from tyrosine |
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Definition
Tyrosine -> DOPA DOPA -> Dopamine Dopamine -> NE NE -> EPI |
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Term
| What are the roles of COMT and MAO |
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Definition
*involved in the inactivation of catecholamines *COMT (catechol-O-methlytransferase) and MAO (monoamine oxidase) are both used in the inactivation of NE, EPI, and dopamine *Serotonin is only inactivated by MAO and not COMT |
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Term
| What do the amino acids trytophan and glutamic acid lead to? |
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Definition
*Tryptophan is the precursor to serotonin and the pineal hormone melatonin *glutamic acid is converted to histamine |
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Term
| How does negative feedback work in tropic and releasing hormones? |
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Definition
*Hormones can inhibit the release of tropic hormones from the anterior pituitary *Hormones can also inhibit the release of releasing hormones from the hypothalamus |
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Term
| What are the basics of steroid hormones? |
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Definition
*all steroid hormones are derived from cholesterol and differ only in the ring structure and side chains attached to it *all steroid hormones are lipid soluble |
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Term
| What are the different types of steroid hormones? |
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Definition
*glucocorticoids, ex - cortisol *mineralcorticoids, ex - aldosterone *androgens, ex - testosterone *estrogens, ex - estradiol and estrone *progestogens (progestins), ex - progesterone |
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Term
| How are steroid hormones transported? |
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Definition
*not water soluble so they are carried in the blood complexed to specific binding globulins *corticosteroid binding globulin carries cortisol *sex steroid binding globulin carries testosterone and estradiol |
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Term
| Explain steroid hormone synthesis |
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Definition
*all steroid hormones are derived from cholesterol *A series of enzymatic steps in the mitochondria and ER of steroidogenic tissues convert cholesterol into all of the other steroid hormones and intermediates *the rate limiting step in this process is the transport of free cholesterol from the cytoplasm into mitochondria. This step is carried out by the Steroidogenic Acute Regulatory Protein (StAR) |
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Term
| Explain the different layers of the adrenal gland? |
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Definition
*adrenal cortex (outer) produces about 50 diff chemicals a) mineralcorticoids in the outer layer b) glucocorticoids and cortisol in the middle layer c) sex hormones (androgens, estrogen) in the innermost layer *adrenal medulla (inner) is where dopamine is converted to NE and/or EPI |
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Term
| Explain the biological actions of glucocorticoids? |
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Definition
*include cortisol, cortisone, corticosterone *primary target tissues are muscle and liver *effects - protein catabolism and gluconeogenesis |
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Term
| Explain the biological actions of mineralcorticoids |
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Definition
*includes aldosterone and 11-deoxycorticosterone *primary target tissue - kidney tubules *effects - sodium retention and potassium excretion |
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Term
| Explain the biological actions of androgens |
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Definition
*includes testosterone, 5alpha-dihydrotestosterone, dehydroepiandrosterone *primary target tissue - reproductive organs (primary and secondary) and muscle *effects - spermatogenesis, secondary male characteristics, bone maturation, virilization |
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Term
| Explain the biological actions of estrogens |
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Definition
*includes estradiol and estrone *primary target tissue - reproductive organs (primary and secondary) *effects - feminization and cyclic rhythms |
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Term
| Explain the biological actions of progestins |
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Definition
*includes progesterone *primary target issue - uterus *effects - nidation and maintenance of pregnancy |
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Term
| What are the important enzymes for cortisol synthesis? |
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Definition
*cytoplasmic 17alpha-hydroxylase (aka 17,20 lyase or CYP17) *cytoplasmic 21-hydroxylase (aka CYP21A2) *mitochondrial 11beta-hydroxylase(aka CYP11B1) |
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Term
| How do hormones regulate genes? |
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Definition
*Genes regulated by steroid hormones posses binding regions in the sequence called steroid hormone response elements (HREs) *when steroid is absent - receptor is bound and "guarded" by chaperone proteins; transcription does not occur *when steroid is present - steroid displaces the chaperone receptor, binds the receptor, and binds the HRE sequence; transcription begins |
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Term
| What are androgens and glucocorticoids excreted as? |
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Definition
*androgens excreted as 17-ketosteroids *glucocorticoids excreted as 11-oxy-17-ketosteroids *they are markers for their respective hormones |
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Term
| What's the storage duration of different hormones in the cell? |
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Definition
*Steroids and 1,25(OH)2-D3 - none *catecholamines and PTH - hours *insulin - days *T3 and T4 - weeks |
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Term
| What are the steroid binding proteins? |
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Definition
*Corticosteroid binding globulin (CBG) binds cortisol avidly and corticosterone less avidly *Sex hormone binding globulin (SHBG) binds testosterone avidly and estradiol less avidly |
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Term
| Which steroid hormones are not derived from cholesterol through pregnenolone? |
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Definition
*Retinoic acid is derived from Vitamin A (Vitamin A consists of retinol, retinal, and retinoic acid) *Vitamin D is derived from cholesterol but not through pregnenolone |
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Term
| How is Vitamin D3 formed? |
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Definition
*In skin, 7-dehydrocholesterol (provitamin D3) undergoes nonenzymatic photolysis by UV light to form previtamin D3 *in the liver its converted to 25-hydroxycholecalciferol *other hydroxylations to 1,25-dihydroxy vitamin D3 (the active form) occur in the kidneys |
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Term
| What's the function of Vitamin D? |
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Definition
| *Vitamin D3 (aka calcitrol) functions primarily to regulate calcium and phosphorous homeostasis |
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